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Abstract: V letu 2023 − eno leto po obsežnem požaru na Goriškem Krasu, ki je divjal julija leta 2022 − smo na izbranih gozdnih vzorčnih ploskvah popisali zeliščno, grmovno in drevesno vegetacijo in analizirali tla do globine 10 cm. Ploskve smo izbrali na lokacijah stalnih vzorčnih ploskev ZGS z različno stopnjo poškodovan osti zaradi požara. Na izbranih ploskvah smo skupno popisali 260 vrst praprotnic in semenk. V drevesni plasti smo popisali trinajst vrst (enajst domorodnih in dve tujerodni), v grmovni plasti trideset, v zeliščni pa 255. V drevesni plasti so bili najpogostejši mali jesen, črni gaber in črni bor, v grmovni mali jesen, navadni ruj in robide. V zeliščni plasti smo med drugimi popisali tudi devetnajst drevesnih vrst, ki so pomembna zasnova pri naravni obnovi požganega gozda na Krasu; najpogostejša sta bila črni gaber in rešeljika. Gradient poškodovanosti po požaru se jasno kaže v večini vegetacijskih in talnih spremenljivk. Statistično značilne razlike med skupinami ploskev z različno stopnjo poškodovanosti smo ugotovili za šest parametrov: pH-vrednosti in vsebnosti žvepla v organskem delu tal, zastiranje drevesne plasti, zastiranje mahov, število vrst v spodnji drevesni plasti, število vrst zeliščne plasti. Na ploskvah smo prepoznali devet (ter še tri vrste na požarišču zunaj ploskev) invazivnih ali potencialno invazivnih tujerodnih rastlinskih vrst; med drevesnimi sta bila najpogostejša robinija in visoki pajesen. Študija pomembno prispeva k razumevanju razvoja vegetacije, pomlajevanja ključnih drevesnih vrst in poškodb gozdnih tal v inicialni fazi po obsežnem požaru.
Keywords: gozdna vegetacija, poškodbe tal, gozdni požar, drevesne vrste, pestrost vrst, invazivne rastlinske vrste, Kras, Slovenija
Published in DiRROS: 21.05.2024; Views: 10; Downloads: 3
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Abstract: Although secondary ion mass spectrometry (SIMS) is a versatile method used in the fields of surface analysis, depth profiling and elemental and molecular mapping, it also lacks quantification capabilities. The main reason for this is the matrix effect, which influences the ionization yield of secondary ions with respect to the substrate from which the analyzed compounds originate. There are several approaches to reduce the matrix effect, and gas flooding is one of the easiest methods to apply. In this work, we have investigated the possibilities of the ToF-SIMS method for the quantification of selected metals and alloys containing these metals in different ratios by reducing the matrix effect in the presence of different atmospheres. The measurements were performed in the ultra-high vacuum (UHV) environment, H2 and O2 atmospheres. H2 flooding shows the most significant improvements compared to the UHV analysis, while O2 is also promising but has some limitations. Improvements are most evident for the transition metals Ti, Cr, Fe, Co and Ni employed in our study, while the p-block elements such as Al and Si do not change so extensively. The deviations from the true atomic ratios of selected transition metals in different alloys reach a maximum of only 46 % when analyzed in the H2 atmosphere. In contrast, these values are 66 and 228 % for the O2 atmosphere and UHV environment, respectively. Our results suggest that gas adsorption and consequent formation of a new matrix on the surface, especially in the case of hydrogen, reduces the differences between the different chemical environments and electronic structures of the surface. In this way, the quantitative aspects of the SIMS method can be improved.
Keywords: ToF-SIMS quantification, H2 and O2 gas flooding, matrix effect reduction, cluster secondary ions
Published in DiRROS: 15.05.2024; Views: 72; Downloads: 37
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Abstract: Background. Thyroid cancer is one of the most common secondary cancers after treatment of malignancy in childhood or adolescence. Thyroid gland is very sensitive to the carcinogenic effect of ionizing radiation, especially in children. Imbalance between pro- and anti-oxidant factors may play a role in thyroid carcinogenesis. Our study aimed to assess the relationship between genetic variability of antioxidant defence-related genes and the risk of secondary thyroid cancer after treatment of malignancy in childhood or adolescence. Patients and methods. In a retrospective study, we compared patients with childhood or adolescence primary malignancy between 1960 and 2006 that developed a secondary thyroid cancer (cases) with patients (controls), with the same primary malignancy but did not develop any secondary cancer. They were matched for age, gender, primary diagnosis and treatment (especially radiotherapy) of primary malignancy. They were all genotyped for SOD2 p.Ala16Val, CAT c.-262C>T, GPX1 p.Pro200Leu, GSTP1 p.Ile105Val, GSTP1 p.Ala114Val and GSTM1 and GSTT1 deletions. The influence of polymorphisms on occurrence of secondary cancer was examined by McNemar test and Cox proportional hazards model. Results. Between 1960 and 2006 a total of 2641 patients were diagnosed with primary malignancy before the age of 21 years in Slovenia. Among them 155 developed a secondary cancer, 28 of which were secondary thyroid cancers. No significant differences in the genotype frequency distribution were observed between cases and controls. Additionally we observed no significant influence of investigated polymorphisms on time to the development of secondary thyroid cancer. Conclusions. We observed no association of polymorphisms in antioxidant genes with the risk for secondary thyroid cancer after treatment of malignancy in childhood or adolescence. However, thyroid cancer is one of the most common secondary cancers in patients treated for malignancy in childhood or adolescence and the lifelong follow up of these patients is of utmost importance.
Keywords: secondary thyroid cancer, antioxidant genes, genetic polymorphism
Published in DiRROS: 09.05.2024; Views: 72; Downloads: 47
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Keywords: ToF-SIMS kvantifikacija, kovine, matrični efekt, preplavljanje, atmosferski plini
Published in DiRROS: 09.05.2024; Views: 72; Downloads: 34
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Published in DiRROS: 30.04.2024; Views: 87; Downloads: 132
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